﻿//-----------------------------------------------------------------------
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//-----------------------------------------------------------------------
namespace AbstractSaaSTemplate.Infrastructure.Win2K8WithSQLServer.Repositories{    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using AbstractSaaSTemplate.Domain.Models.Entities;
    using AbstractSaaSTemplate.Domain.Models.ValueObjects;
    using AbstractSaaSTemplate.Domain.Repositories;

    /// <summary>
    /// Implements 'IMessagesRepository' and all its contract, providing
    /// data accessibility to the aggregate 'Messages'.
    /// </summary>
    public sealed class MessagesRepository : SQLServerConnectedRepositoryBase, IMessagesRepository
    {
        /// <summary>
        /// Initializes a new instance of the MessagesRepository class.
        /// </summary>
        /// <param name="loaderForConnectionString">The delegate capable of retrieving the connection string for the EF4 context.</param>
        public MessagesRepository(Func<string> loaderForConnectionString)
            : base(loaderForConnectionString)
        {
        }

        /// <summary>
        /// Gets a number of messages to dispatch and mark them
        /// as invisible for a period of time, to avoid two instances
        /// working on the same messages when scaling up the number of servers.
        /// </summary>
        /// <param name="numberOfMessages">Defines the number of messages that should be retrieved.</param>
        /// <param name="keepInvisibleForSeconds">Keeps all messages consumed by this method for the number of seconds defined, avoiding that this message is consumed by another queue.</param>
        /// <returns>Returns a list of Message to be dispatched.</returns>
        public IEnumerable<Message> GetMessagesReadyToDispatch(
            int numberOfMessages,
            int keepInvisibleForSeconds)
        {
            using (var context = NewContext())
            {
                var now = DateTime.Now;
                var messageReadyToDispatch = context.Messages
                    .Where(d =>
                        (!d.DoNotDispatchBefore.HasValue || d.DoNotDispatchBefore <= now) &&
                        (!d.InvisibleUntil.HasValue || d.InvisibleUntil <= now) &&
                        (!d.DispatchedAt.HasValue))
                    .OrderByDescending(d => d.Priority)
                    .OrderByDescending(d => d.CreatedAt)
                    .Take(numberOfMessages)
                    .ToArray();

                // make all messages invisible for a few seconds
                // that will avoid that the same message is taken
                // twice by any consumer of this queue.
                var invisibleUntil = now.AddSeconds(keepInvisibleForSeconds);
                foreach (var message in messageReadyToDispatch)
                {
                    message.InvisibleUntil = invisibleUntil;
                }

                // now we save the invisibility date to everything.
                context.SaveChanges();

                // now we prepare the returning list of entities.
                var entities = new List<Message>();
                foreach (var message in messageReadyToDispatch)
                {
                    var typeOfToAddressList = Type.GetType(message.ToAddressListType);
                    var toAddressList = (IEnumerable<MessageDestination>)message.ToAddressList.FromXml(typeOfToAddressList);

                    var typeOfFromAddress = Type.GetType(message.FromAddressType);
                    var fromAddress = (MessageDestination)message.FromAddress.FromXml(typeOfFromAddress);

                    var typeOfCustomData = Type.GetType(message.CustomDataType);
                    var customData = (MessageCustomData)message.CustomData.FromXml(typeOfCustomData);
                    
                    var entity = new Message(
                        fromAddress,
                        toAddressList,
                        customData);

                    CopyFromEF4ToDomain<Core.Message, Message>(
                        message,
                        entity);

                    entities.Add(entity);
                }

                // finally we return the entities.
                return entities;
            }
        }

        /// <summary>
        /// Schedules the dispatch of a message.
        /// </summary>
        /// <param name="entity">The message that will be scheduled for dispatch.</param>
        public void ScheduleMessageForDispatch(Message entity)
        {
            this.ScheduleMessageForDispatch(entity, DateTime.MinValue);
        }

        /// <summary>
        /// Schedules the dispatch of a message.
        /// </summary>
        /// <param name="entity">The message that will be scheduled for dispatch.</param>
        /// <param name="doNotSendBefore">Date from which this message can be sent.</param>
        public void ScheduleMessageForDispatch(Message entity, DateTime doNotSendBefore)
        {
            if (entity == null)
            {
                throw new ArgumentNullException("entity");
            }

            // we initialize the Id if that hasn't yet been.
            if (entity.Id == Guid.Empty)
            {
                entity.Id = Guid.NewGuid();
            }

            using (var context = NewContext())
            {
                var message = context.Messages
                    .Where(d => d.Id == entity.Id)
                    .FirstOrDefault();

                if (message == null)
                {
                    message = new Core.Message();
                    message.Id = entity.Id;
                    context.Messages.AddObject(message);
                }

                // if there is a date until when we need to
                // wait before dispatch, we set it.
                if (doNotSendBefore != DateTime.MinValue)
                {
                    message.DoNotDispatchBefore = doNotSendBefore;
                }
                else
                {
                    message.DoNotDispatchBefore = null;
                }

                // we copy all data that is possible to copy from the 
                // domain entity which is, in this particular case, not much
                CopyFromDomainToEF4<Message, Core.Message>(
                    entity,
                    message);

                // get type names for destination and custom data.
                var customDataTypeName = GetQualifiedName(entity.CustomData.GetType());
                var fromAddressTypeName = GetQualifiedName(entity.FromAddress.GetType());
                var toAddressListTypeName = GetQualifiedName(entity.ToAddressList.GetType());

                // we save the value object type and the destinations
                // data into serialized fields, that can be used later
                // to return the typed destinations that we are saving.
                message.FromAddressType = fromAddressTypeName;
                message.FromAddress = entity.FromAddress.ToXml();

                message.ToAddressListType = toAddressListTypeName;
                message.ToAddressList = entity.ToAddressList.ToXml();

                // then we save the value object type and the custom
                // data into serialized fields, that can be used later
                // to return the typed custom data that we are saving.
                message.CustomDataType = customDataTypeName.ToString();
                message.CustomData = entity.CustomData.ToXml();

                // finally we save it all in the database
                context.SaveChanges();
            }
        }

        /// <summary>
        /// Marks the message as dispatched.
        /// </summary>
        /// <param name="id">The id of the message.</param>
        public void MarkMessageAsDispatched(Guid id)
        {
            using (var context = NewContext())
            {
                var message = context.Messages
                    .Where(d => d.Id == id)
                    .FirstOrDefault();

                if (message != null)
                {
                    message.DispatchedAt = DateTime.Now;
                    context.SaveChanges();
                }
            }
        }

        /// <summary>
        /// Gets the qualified name of a type without version and public token.
        /// Missing this information you can retrieve the type using Type.GetType
        /// even if the version of these classes change.
        /// We save other data that is specific for this infra-structure
        /// here it's important to advise: if you save the 'AssemblyQualifiedName'
        /// all alone, whenever you shift the version number of your domain, all
        /// old types will stop working, because the qualified name includes the version.
        /// for that to possibly work, we remove a few items from the qualified name
        /// such as version number and public token.
        /// </summary>
        /// <param name="type">The type that will be extended.</param>
        /// <returns>Returns a AssemblyQualifiedName without public token and version number.</returns>
        private static string GetQualifiedName(Type type)
        {
            if (type == null)
            {
                throw new ArgumentNullException("type");
            }

            var typeQualifiedNameFrags = type.AssemblyQualifiedName.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
            var typeQualifiedName = new StringBuilder();
            foreach (var frag in typeQualifiedNameFrags)
            {
                if (!frag.TrimStart().StartsWith("Version", StringComparison.OrdinalIgnoreCase) &&
                    !frag.TrimStart().StartsWith("PublicKeyToken", StringComparison.OrdinalIgnoreCase))
                {
                    if (typeQualifiedName.Length != 0)
                    {
                        typeQualifiedName.Append(", ");
                    }

                    typeQualifiedName.Append(frag);
                }
            }

            return typeQualifiedName.ToString();
        }
    }
}


